An antenna is an energy converter, which can transform a guided wave propagated on a transmission line into a spatial electromagnetic wave, or perform inverse transformation. The antenna is used to transmit or receive an electromagnetic wave in wireless communication. Most common conventional antennas in a wireless communications system are: a fiberglass omnidirectional antenna, a directional panel antenna, a small whip antenna, and the like. In most cases, people require that an antenna should have a maximum coverage area and a farthest coverage distance, that is, the antenna has a maximum beam width and a maximum gain, both of which, however, are contradictory for a single-beam antenna.
A multi-beam antenna has a multi-beam radiation capability, which may increase a radiation coverage area without decreasing an antenna gain. However, a radiation coverage area of a conventional multi-beam antenna is still relatively small.